Automatic Height Control repair

[CS43FI]

Hello

I tried to search about the topic "Auto Height Control" and for my surprise found no posts about actually repairing the inoperative system. Please inform if You are aware of one, I'm interested in more information.

I have 1978 New Yorker Brougham with the mentioned system. I have narrowed the problems to control valve and the vacuum operated compressor. I have the 1978 FSM, but it has very little information of the system. Of course in the event of compressor failure, everything must be replaced as a unit...

By the way, I found the control valve in the rear wheel well to be very obsolete and undocumented. Hard to find any information about it, but I believe I can find suitable replacement for that.

The compressor kind of works - Turns slowly when vacuum is applied and makes erratic pressure sometimes. May achieve 10 psi of 150 psi rated. I disassembled the compressor and found 2 o-rings, which were dried. There were also 2 felt o-rings, which seem to disintegrate if touched. I may be able to find imperial o-rings that fit - information on exact dimensions will be appreciated. Could anyone tell more about the felt ones and the lubrication? Lubricant has dried decades ago but what I can tell, there should be some. The outlet check valve is hardened and should be replaced with a rubber ball of same sort.

I'm also interested if someone has made entirely new compressor arrangement. For example 12V compressor with pressure switch stuffed into original location. That could be the backup plan if the original compressor turns out to be too difficult to repair.

Thanks for Your help in advance!

 

[CBODY67]

GM was still installing automatic level mechanisms into the 2000s. Probably still are? My 2005 Buick LeSabre LImited has one. Park Avenues should too, plus Cadillac DeVilles/DTS models. I suspect these would be electric.

Look in the Chrysler MasterTech videos at www. mymopar.com or possibly on YouTube for explanation and functioning of your OEM system. Seems like Dorman Products was still selling the compressors for some vehicles, but a bit pricey.

Just some thoughts,
CBODY67

 

[Justin Plant]

Last of the line Panther Platform Fords and it's cousins could be had with rear height control. If you happen across one in a junkyard the compressor is under a plastic cover behind the driver's headlight. The shocks, hoses and repair clips are all still available.

 

[rags]

there's no shortage of 12v air compressors out there. the air ride and "on-spot" systems in the trucks i work on use them.

 

[Mbaird]

GM was still installing automatic level mechanisms into the 2000s. Probably still are? My 2005 Buick LeSabre LImited has one. Park Avenues should too, plus Cadillac DeVilles/DTS models. I suspect these would be electric.

Look in the Chrysler MasterTech videos at www. mymopar.com or possibly on YouTube for explanation and functioning of your OEM system. Seems like Dorman Products was still selling the compressors for some vehicles, but a bit pricey.

Just some thoughts,
CBODY67

That Master Tech video is really good . I have watched dozens of them . Actually not to different than the traing videos they had in the 80s when I worked at a Dodge dealership.

 

[fury fan]

there's no shortage of 12v air compressors out there. the air ride and "on-spot" systems in the trucks i work on use them.

On-spot - the automatic tire chain device? I worked at a utility-truck builder many years ago and we installed a few on some snow-state trucks. (but only a handful at most)
I loved the simplicity of how they used an air brake chamber and the rotating tire to drive the chains. Genious!


As for the load-leveling -
Yes, there is a ton of aftermarket stuff out there, might make more sense than trying to repair the original items.
Lincoln Mark 7 and 8 had air-rides susp, might be able to find parts from them. They are antiques themselves at this point, but might be some good aftermarket support for them.

 

[rags]

On-spot - the automatic tire chain device?

yes. i checked the shelf at work today and found an on-spot unit. it's a 12v thomas. recently replaced a compressor on a kelderman 4 bag rear air suspension. the unit they supplied looked just like this unit available through amazon. Amazon product ASIN B07TJ88DK4

 

[kmccabe56]

Hello

I tried to search about the topic "Auto Height Control" and for my surprise found no posts about actually repairing the inoperative system. Please inform if You are aware of one, I'm interested in more information.

I have 1978 New Yorker Brougham with the mentioned system. I have narrowed the problems to control valve and the vacuum operated compressor. I have the 1978 FSM, but it has very little information of the system. Of course in the event of compressor failure, everything must be replaced as a unit...

By the way, I found the control valve in the rear wheel well to be very obsolete and undocumented. Hard to find any information about it, but I believe I can find suitable replacement for that.

The compressor kind of works - Turns slowly when vacuum is applied and makes erratic pressure sometimes. May achieve 10 psi of 150 psi rated. I disassembled the compressor and found 2 o-rings, which were dried. There were also 2 felt o-rings, which seem to disintegrate if touched. I may be able to find imperial o-rings that fit - information on exact dimensions will be appreciated. Could anyone tell more about the felt ones and the lubrication? Lubricant has dried decades ago but what I can tell, there should be some. The outlet check valve is hardened and should be replaced with a rubber ball of same sort.

I'm also interested if someone has made entirely new compressor arrangement. For example 12V compressor with pressure switch stuffed into original location. That could be the backup plan if the original compressor turns out to be too difficult to repair.

Thanks for Your help in advance!

The Master Tech video is available online and details operation of the entire system. The o-rings in the compressor that have failed, are most likely easily replaced if you find a shop that repairs hydraulic cylinders. Given that everything is 45 or so years old, you most likely need to replace the rubber line running from the brake booster to the compressor itself, as well as the flexible lines that run to the air shocks themselves from the valve. If you feel the valve is not working, take it into a truck shop that works on semi trailers. It apparently is a common truck part and the parts counter guy might very well have one in stock. Check the air pressure reservoir located in the middle of the car inboard of the left rocker panel. Might be worthwhile pulling it as well, cleaning/wire wheeling it, painting it (POR15) and pressure testing it in the kitchen sink with 10-15psi of pressure to check for air bubbles. I was very surprised to recently find that the system in my car actually works. I have replaced the air shocks (make sure to transfer the heat shield from the old left one to the new left one), ran new lines to it from the valve, and have scored a NOS link from the valve to the rear axle along with the bracket that spring shackle fits through. Lastly, have a good look at the steel lines that run to and from the reservoir and the valve, if they're rusty/crusty, it wouldn't hurt to get new ones bent up. Nothing lasts forever.

 

[kmccabe56]

yes. i checked the shelf at work today and found an on-spot unit. it's a 12v thomas. recently replaced a compressor on a kelderman 4 bag rear air suspension. the unit they supplied looked just like this unit available through amazon. Amazon product ASIN B07TJ88DK4View attachment 619045

If you opt to use this instead of the OE compressor, you need to ensure that you control the power to it so that it doesn't just keep running and blow something out.

 

[rags]

you need to ensure that you control the power to it so that it doesn't just keep running and blow something out.

absolutely. those systems use pressure switches to limit pressure. i have the part number for the nason switch that on-spot uses if anyone is interested.

 

[fury fan]

Relays, relays, relays!
Relays are the ladder logic of our analog cars.

 

[CS43FI]

Hello. Thanks for all of Your contribution. There were numerous options for alternative compressor. I'm afraid there's no junkyard with Panther Platform Ford (or any interesting car whatsoever) sitting around in my part of the World. I may proceed with the new product solution if necessary. If someone has actually installed modern compressor to original location in C-body, please provide us a photo.

I have watched the MTSC library several times, but never paid attention to "Volume 75-7 The New Automatic Height Control System". That gave some further information about inside parts of the compressor to be checked. Thanks for that.

 

[rags]

if the height control valve needs to be replaced with something from the aftermarket, new mechanical valves are available from haldex and velvac. i remember that there were air horn setups that used vacuum powered compressors but i haven't been able to find much info on them.

 

[CS43FI]

Update on this progress.

To clarify the situation: This kind of items are not available right off the shelf here in Europe.

I ordered new delay type height control valve Hadley H450CE equivalent, which bolted right on the place.
I emphasize that this is cheap aftermarket part. I found no delay at all when moving lever by hand - FSM mentions about delay up to 1min. On the other hand I found out no issues when driving on the road so the testing continues...

I adjusted the arm to FSM spec and found out that on normal load no air enter the shocks - the system is purged. Only after considerable amount of load does the air enter. Therefore I don't understand how is the system going to keep 15 PSI minimiun pressure inside shocks when no load is applied. I can of course tweak the arm adjustment to make the operation acceptable.

 

[CBODY67]

Interesting substitution. I suspect the minimum pressure spec on the air shocks is to keep the air bag fully inflated during normal use, without raising the car. From my experience on my '70 Monaco Brougham, it takes over 30psi to raise the rear of the car at all, above normal ride height.

Somewhere in the system, there should be a minimum air pressure sensor that will run the pump until the 15psi level is reached, with each key-start cycle. Getting the system powered-up and operational. Once the minimum pressure at ride height is achieved, the pump stops.

If any "delay" in the system exists, it is to ensure the perceived load is "real" and not just a "bump" in the road that has compressed the rear suspension.

Thanks for the update!

CBODY67

 

[CS43FI]

Interesting comment, since I find the substitution particulary uninteresting. The replacement unit is like 1:1 original unit and bolts right on place - Just to let anyone know. After watching MTSC multiple times and taking note of every word and frame I came up with the solutions to my problems.

The 15 PSI residual pressure is held by check valve, which lives inside dump line connector. Once the air enters the shock, only part of it can escape due to check valve spring pressure. Aftermarket valve lacks dump check valve and shocks were completely purged. Original check valve bolted right on place on the new unit.

Lack of delay was due to fact that there was absolutely no silicone fluid inside dampening unit of the aftermarket valve. As I mentioned, this is a cheap unit and it shows. There were no filling port either so I had to take the valve apart and pour the fluid from old valve through stem opening. Every last drop had to be used to fill the cavity completely and expel air. I received suggestion that RC car differential oil with high viscosity might be same stuff and suitable for this application but this is yet to be confirmed.

Fluid filling meant that the delay works as promised. There's few seconds delay, which should be enough to cancel suspension action on the road. Viscosity of the fluid affects the delay time.

The vacuum compressor was repaired by new piston o-rings. Metric o-ring dimensions were 25 mm (id) x 3,5 mm and 12 mm x 3,5 mm. Latter was not available so I used 11 mm x 3,5 mm which was a bit shy on size. Few wraps of electrical tape on the bottom of o-ring groove solved the problem. Felt o-rings were replicated by cutting strips of self adhesive EPDM sheet t = 5mm. I figured out that these just scrape the lubricant and do not have to be completely air-tight. I lubricated the bores with white lithium grease. If You have better suggestions, please let me know. Pump now makes pressure and stops when outlet is plugged. Actual operation in real driving conditions is to be determined during next months. No photos of the pump, I was too excited to assemble everything.